title: Evolution of fluorescence resonance energy transfer between close-packed CdSeS quantum dots under two-photon excitation.
abstract: Energy transfer (ET) processes between quantum dots (QDS) were investigated by means of steady-state and time-resolved up-conversion luminescence measurements. Two types of CdSeS QDs with different Se/S molar ratios at the similar sizes of ~4.5 nm emit green and orange up-conversion luminescence at infrared laser excitation, separately. The power dependence and nanosecond luminescent decays of QDs films demonstrated that up-conversion luminescence was attributed to two-photon absorption and ET process occurred from green-emitting QDs to orange-emitting QDs. The ET rate was estimated quantitatively to be 0.03 ns(-1) by Dexter theory. The decrease of ET rate is due to Se doped substituted in the Sulfur sites. The band-edge excitonic state is predominating at the initial time evolution and responsible for peak shift and ET. The surface emission of orange-emitting QDs becomes slower, and is attributed to the trapping of electrons from QDs donors.
authors.affiliation: School of Electronic Engineering, Heilongjiang University, Harbin 150080, China.
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Wu
authors.forename: Hong-An
authors.initials: HA
authors.lastname: Ye
authors.forename: Yachen
authors.initials: Y
authors.lastname: Gao
authors.forename: Qing
authors.initials: Q
authors.lastname: Chang
authors.forename: Zhiren
authors.initials: Z
authors.lastname: Zheng
authors.forename: Yanqiang
authors.initials: Y
authors.lastname: Yang